This invention relates generally to clips for use in closing blood vessels during surgical procedures. More particularly, this invention relates to a metallic, ligating clip which, in time, is absorbed by the body in which it is positioned, thereby avoiding the necessity of reopening a wound closure to remove the clip, and to an applicator for applying same.
In the early part of the twentieth century, the desirable bio-absorbable properties of magnesium were initially suggested as a potential beneficial material for use in sutures and ligatures, as discussed in Andrews, E. W.: Absorbable Metal Clips as Substitutes for Ligatures and Deep Sutures, J.A.M.A. 69:278 (July 28, 1917). However, a later study including in vivo and in vitro tests indicated that while magnesium wire was a desirable material because of its absorbability by the human body, its ultimate conclusion was that undesirable properties of gas formation during absorption, and hemolysis of blood cells found during prolonged contact with magnesium, in vitro, were potentially greater than the proposed benefits. M. G. Seelig, MD: A Study of Magnesium Wire as an Absorbable Suture and Ligature Material, Arch. Surg. 8:669-680, 1924. After this second article, discussion in the literature of the use of magnesium wire for suture or ligature material ceased, as far as is known. Additionally the Seelig article dealt solely with the use of an absorbable metal as a wire which could be knotted by a doctor applying the suture or ligature. The Seelig article does not address itself to ligature clips, which requires less metal deformation during application than does a suture.
While the use of metallic hemostatic clips has increased over the years, the development of stable, unchanging metal clips made of silver, and later tantalum, which would not degrade when position in the body has been of prime importance. However, the use of such clips during surgery, may require a later second operation in order to remove those clips from the patient's body after certain healing has taken place. Such a stable, non-absorbable hemostatic clip is shown in U.S. Pat. No. 3,363,628.
It is understood that heretofore known stable metallic ligature clips are considered by many doctors to be incompatible with the use of computer anatomical tomography (Cat Scan) equipment. Metal clips interfere with the passage of signals through the body in order to provide the computer generated pictures. Such pictures are especially important in viewing the healing process and the detection of diseases such as, cancer.
Partially in response to the above noted problem, a non-metallic absorbable ligating clip which degrades and is absorbed by the body after a predetermined period of time eliminating the possible need for a second operation to remove the clips was developed, as disclosed in Schaefer and Geelhoed, Surgery, Gynecology and Obstetrics, April, 1982, Volume 154, 513-516. The non-metallic clips disclosed are made of an extruded polymer flexible monofilament structure which may be clamped around a ligature. However, the elasticity of the material requires that a mechanical locking structure be designed into the clip, thus making the clip larger than previous metallic ligating clip, which would maintain its crimped or closed position once it was plastically deformed. As a result of the increased size of existing non-metallic absorbable ligating clips, blood vessels must be isolated from surrounding body tissues or organs to allow the clamp to be fastened onto the blood vessel and the locking mechanism closed thereon. There exists multiple instances where the use of the above, mentioned clips are impossible due to interferance of the locking mechanism by surrounding tissues.
Meanwhile, research directed to other areas than sutures and ligature clips, disclosed that the use of a magnesium tube as a prostheses for replacing a part of an animal's aorta showed no toxicity in the system when implanted therein. Sawyer et al, Long-term Patency of Solidwall Vascular Prosthesis, Archives of Surgery, Volume 91, November, 1965, 735-742. Additional articles in the technical literature indicate that the use of magnesium in orthopedics, while yielding no adverse side effects, is not a desirable material for use as screws, rods, etc. in bone healing, as it is absorbed faster than the bone healing process takes place.
A need has developed for an improved absorbable ligature clip which maintains a closed position once placed over a blood vessel and closed thereon without the need for a locking mechanism on the ligature clip itself.
It is therefore, an object of the present invention, generally stated, to provide a new and improved absorbable metal ligature clip.
Another object of the present invention is the provision of an absorbable metallic ligating clip, including means for preventing destructive crimping thereof when position around a ligature.